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GSFC STROZ Lidar at MOHAVE 2009

GSFC STROZ Lidar at MOHAVE 2009. Laurence Twigg, Thomas J. McGee and Grant Sumnicht Code 613.3, Goddard Space Flight Center. Lidar Trailer at TMO for MOHAVE-2009. STROZ- Lite NDACC Mobile Lidar. Originally Ozone, Aerosol and Temp instrument XeCl Excimer laser - 308 nm Nd-YAG laser @ 355 nm

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GSFC STROZ Lidar at MOHAVE 2009

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  1. GSFC STROZ Lidar at MOHAVE 2009 Laurence Twigg, Thomas J. McGee and Grant Sumnicht Code 613.3, Goddard Space Flight Center L. Twigg, et al.

  2. Lidar Trailer at TMO for MOHAVE-2009 L. Twigg, et al.

  3. STROZ-Lite NDACC Mobile Lidar Originally Ozone, Aerosol and Temp instrument XeCl Excimer laser - 308 nm Nd-YAG laser @ 355 nm 2004 - 408nm and 387 Lo channels added for water vapor demonstration at MLO 2005 – campaign at TMF – first comparisons with other lidar WAVES Campaign 2008 2009 MOHAVE Campaign L. Twigg, et al.

  4. Significant Changes in STROZ-Lite Mobile Lidar(Between MOHAVE 2007 and MOHAVE 2009) Change Spectra-Physics YAG for Continuum – higher power; better polarization characteristics Excimer Laser had new pressure vessel installed New PMT bases (Licel) Mini Receiver for H2O channels – low altitude return Calibration Lamp AT lidar – new beam splitter (not tested during MOHAVE-2009) L. Twigg, et al.

  5. STROZ NDACC Mobile LidarStatus during MOHAVE-2009 Major problems with laser systems (YAG and Excimer) Continuous testing lead to many configuration changes These changes included FOV settings, PMT changes as well as blocker filter use for H2O test By Last third of campaign achieved “stability” T-O3 configurations alternated with 355 blocker filter use for H2O fluorescence testing. Thus time coincidences with sonde launches were used for both O3 and H2O profile comparisons. AT lidar – similar problems led to only 1 night with 2 hrs of engineering data, thus changes to test elimination of H2O fluorescence problem were never tested. L. Twigg, et al.

  6. STROZ System Parameters * During MOHAVE, both the STROZ and the AT Lidar used an iris to provide a variable Field of View. These are the calculated FOV used for WV measurements based on a measurement of the iris diameter at the various détentes. Recent data indicate that this introduces errors. New fixed apertures installed L. Twigg, et al.

  7. STROZ-Lite –TMF-2005 Calibration STROZ STROZ Hi-Pair Calibration Constant Mean = 217.1 SD = 14.4 (6.6%) • Lidar calibrated against local, synchronous RS-92 launches • Calibration constant determined between 2 – 3 km above lidar • If sharp features were noted, a different range was selected • STROZ H2O Measurements at 2.3 mRad FOV L. Twigg, et al.

  8. STROZ-Lite MOHAVE-2009 Calibration Factors STROZ • During MOHAVE-2009, The STROZ lidar operated in two modes – the Ozone Mode with FOV 2.3; and the Water vapor mode – FOV 1.0 • The Mean value of the Lo-Pair Cal Factor was 13.3 +/- 9%, which leads to a value for the Hi-Pair Cal Factor of 215 +/- 5% • Compare this with the MOHAVE-2005 value of 217 +/- 7 L. Twigg, et al.

  9. Fluorescence in STROZ WV October 20/21, 2009 L. Twigg, et al.

  10. STROZ-Lite vs. RS92-Corr. Sonde Blocked Unblocked L. Twigg, et al.

  11. STROZ-Lite vs. CFH Blocked Unblocked L. Twigg, et al.

  12. STROZ vs. JPL-WV Unblocked Blocked L. Twigg, et al.

  13. STROZ-Lite vs. ALVICE Blocked Unblocked L. Twigg, et al.

  14. Issues Noted during MOHAVE and Later Tests • One PMT showed long term increase in output with “constant” signal – needed to replace PMT but not base – Not a WV channel • All channels in the AT system are apparently not aligned the same – showed up in changing ratios with change in FOV • Changing the AT FOV was not repeatable • Detents not “kinematic” • Vanes in iris may stick • A constant signal does not give the same number of counts in different Licel photon counting modules • Cal lamp signal into one channel was moved from one counter to another • All PMT parameters kept the same • The same discriminator setting was used for all counters L. Twigg, et al.

  15. AT and STROZ-Lite H2O profilesGSFC on 10/8/2010 – 2 Hr Averages L. Twigg, et al.

  16. H2O Summary Comparison of blocked vs. unblocked STROZ-Lite H2O profiles during MOHAVE-2009 show effects consistent with fluorescence. Effect seen in comparisons vs. sondes and other lidar systems. New observations obtained after modifications applied to both AT and STROZ systems show current H2O profiles for both blocked and unblocked observation modes yield the same result! However – this is still not proof that ALL fluorescence has been eliminated (could different telescope mirrors/coatings be giving the same effect???). Thus there is a need for a new (TMO) campaign to acquire long integrations at a dark site (no moon) in order to see if any fluorescence still exists in either mobile lidar system. Need to further examine roles of smoothing window, background definition, residual fluorescence on H2O profiles. Use corrected RS92 sondes??? Add “Blocked” or “Unblocked” to 60 min files. L. Twigg, et al.

  17. STROZ-Lite Temperature Profiles during MOHAVE 2009 Same observational issues as with H2O, i.e. configuration changes, sonde launch time coincidences, etc. Reminder - changes included FOV settings, PMT changes as well as blocker filter use for H2O test Last 5 days of campaign – always acquired 2 hr of T-O3 data using large (2.3 mrad) FOV Reminder – no AT lidar temperature profiles – various system problems led to only 1 night with 2 hrs of engineering data MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct. 18-21, 2010 L. Twigg, et al.

  18. STROZ-Lite vs. RS92_Corr. Sonde L. Twigg, et al.

  19. STROZ-Lite vs. CFH L. Twigg, et al.

  20. STROZ-Lite vs. FPH L. Twigg, et al.

  21. STROZ-Lite Vs. JPL Temperature L. Twigg, et al.

  22. STROZ-Lite vs. ALVICE Temperature L. Twigg, et al.

  23. Temperature Summary Good agreement with sondes and other lidar systems. Some comparisons show ~1-2 cold bias at 15-20 kms Limited T data – longer campaign useful Algorithm changes – time to re-run Thierry’s simulation program??? L. Twigg, et al.

  24. STROZ O3 at MOHAVE 2009 Ozone Comparisons were made with ECC sondes, and the JPL Stratospheric and Tropospheric lidars STROZ lidar had new PMT housings and in one case a completely new photomultiplier tube installed for ozone measurements. Not all ozone measurements were simultaneous with sonde launches due to water vapor measurement constraints and/or system configuration changes. MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct. 18-21, 2010 L. Twigg, et al.

  25. STROZ vs JPL Lidars MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct. 18-21, 2010 Nine nights of comparable lidar measurements Good agreement from 15 to 45 km between STROZ and JPL Stratospheric Lidar Agreement is not as good below 15 km, especially between STROZ and the JPL Trop Ozone lidar – believed to be related to the need to amplify the 308 signals Noise in STROZ profile above 45 km also due to weak 308 signals – this is an electronic issue not a laser power issue L. Twigg, et al.

  26. STROZ FPH Ozone Comparisons MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct. 18-21, 2010 3 comparable FPH launches with ECC sondes Ascent data used for comparisons Reasonable agreement from 13 km to 27 km (mean difference = -3.4%) L. Twigg, et al.

  27. STROZ CFH Ozone Comparisons MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct. 18-21, 2010 5 comparable CFH launches with ECC sondes during MOHAVE Reasonable agreement between 15 and 30 KM – Mean diff = 1.20+/- 1.13 pump correction errors above 30 km? L. Twigg, et al.

  28. Conclusions and Solutions A fixed field stop is necessary – the errors introduced from an uncertain aperture size convolved with slight differences in alignment at different channels are too large. SOLUTION: Kinematic mounts to allow for interchangeable, fixed apertures fabricated and installed in both STROZ and AT lidars. Fluorescence is an issue within the STROZ lidar. SOLUTION: Field lens and collimating lens assembly were fabricated from extremely low fluorescence fused silica – received and installed in STROZ.; may not be necessary for AT Changing or swapping Licel cards changes the calibration – input pre-amplifier issues? All of these needed changes were implemented as of Oct 2010 L. Twigg, et al.

  29. Conclusions and Solutions(Continued) H20 looks much better, but needs more observations for verification O3 looks good above 15 km. Tests indicate that amplification of 308 signals may improve sensitivity below 15 km Testing underway for limitations of O3 using 0.7 mrad aperture (excimer divergence problems) T looks to be ~ 1degree cool on average, BUT night-to-night changes in magnitude – smoothing, DTC issues??? L. Twigg, et al.

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